bump old thread i just rebuilt my 4160 also it has a blank for my carb # R50419-1
my floats weren't level either but they are now. also the rebuild kit came with the 6.5 power valve not the 2.5
it started and ran fine . but i will get it on the lake tuesday for test drive.

any update to your situation hows your carb working for you .

i used the holley rebuild kit 703-29

also the old needle and seats had different numbers on them primary had 97 secondary had 110 stamped on them .in the new rebuild kit both needle and seats are identical .